Liquid crystal display and panel therefor

ABSTRACT

The present invention provides a liquid crystal display having excellent visibility. 
     A thin film transistor array panel is provided, which includes: gate lines formed on an insulating substrate; data lines insulated from the gate lines and intersecting the gate lines; first pixel electrodes disposed on pixel areas defined by intersections of the gate lines and the data lines; first thin film transistors, each having three terminals connected to one of the gate lines, one of the data lines, and one of the first pixel electrodes; second pixel electrodes disposed on the pixel areas and capacitively coupled to the first pixel electrodes; and second thin film transistors, each having three terminals connected to a previous gate line, a storage electrode line or one of the data lines, and one of the second pixel electrodes.

TECHNICAL FIELD

The present invention relates to a liquid crystal display and a paneltherefor.

BACKGROUND ART

A typical liquid crystal display (“LCD”) includes an upper panelprovided with a common electrode and color filters, a lower panelprovided with thin film transistors (“TFTs) and pixel electrodes, and aliquid crystal layer is interposed therebetween. The pixel electrodesand the common electrode are applied with different electric voltages togenerate electric field, thereby changing the orientations of liquidcrystal molecules and thus the transmittance of light passing throughthe liquid crystal layer. As a result, the LCD displays desired images.

However, the LCD has gray inversion that the luminances between graysare reversed and lateral gamma curve distortion that a lateral gammacurve does not coincide with a front gamma curve, thereby exhibitinginferior visibility at left and right view. For example, the luminanceincreases and the color moves into white as goes toward the lateralside. In particular, the luminance difference between bright graysdisappears such that the image is not clear. In the meantime, the recentemployment of the LCD at multimedia increasingly requires goodvisibility for viewing pictures and moving pictures.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more apparent by describingembodiments thereof in detail with reference to the accompanyingdrawings in which:

FIG. 1 is a layout view of a TFT array panel for an LCD according to afirst embodiment of the present invention;

FIG. 2 is a sectional view of the TFT array panel shown in FIG. 1 takenalong the line II-II′;

FIG. 3 is an equivalent circuit diagram of an LCD according to the firstembodiment of the present invention;

FIG. 4 is a layout view of a TFT array panel for an LCD according to thesecond embodiment of the present invention;

FIG. 5 is a sectional view of the TFT array panel shown in FIG. 4 takenalong the line V-V′;

FIG. 6 is an equivalent circuit diagram of an LCD according to thesecond embodiment of the present invention;

FIG. 7 is a layout view of an LCD according to the third embodiment ofthe present invention;

FIG. 8 is an equivalent circuit diagram of an LCD according to the thirdembodiment of the present invention.

FIG. 9 is a layout view of an LCD according to the fourth embodiment ofthe present invention;

FIG. 10 is an equivalent circuit diagram of an LCD according to thefourth embodiment of the present invention;

FIG. 11 is a layout view of a TFT array panel for an LCD according tothe fifth embodiment of the present invention;

FIG. 12 is a layout view of a color filter panel for an LCD according tothe fifth embodiment of the present invention;

FIG. 13 is a layout view of an LCD the fifth embodiment of the presentinvention;

FIG. 14 is a sectional view of the LCD shown in FIG. 13 taken along theline XIV-XIV′;

FIG. 15 is an equivalent circuit diagram of an LCD according to thesixth embodiment of the present invention; and

FIG. 16 is an equivalent circuit diagram of an LCD according to theseventh embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

A motivation of the present invention is to provide a liquid crystaldisplay having excellent visibility.

Technical Solution

Based on the motivation, the present invention divides a pixel electrodeinto two sub-electrodes and applies different voltages to thesub-electrodes.

In detail, a thin film transistor array panel according to an embodimentof the present invention includes a plurality of first signal lines anda plurality of second signal lines insulated from the first signal linesand intersecting the first signal lines formed on the insulatingsubstrate. A plurality of first pixel electrodes are disposed on pixelareas defined by intersections of the first signal lines and the secondsignal lines and arranged in a matrix and a plurality of first thin filmtransistors, each having three terminals connected to one of the firstsignal lines, one of the second signal lines, and one of the first pixelelectrodes, are formed thereon. A plurality of second pixel electrodesare disposed on the pixel areas and capacitively coupled to the firstpixel electrodes, and a plurality of second thin film transistors areformed thereon. Each of the second thin film transistors have a terminalconnected to one of the second pixel electrodes and another terminalconnected to one of the first signal lines that is connected to one ofthe first pixel electrodes in a pixel area in an adjacent row.

The thin film transistor array panel may further include a plurality ofcoupling electrodes that are connected to or overlapping the first pixelelectrodes and overlap the second pixel electrodes with being insulatedtherefrom. The coupling electrodes are preferably connected to drainelectrodes of the first thin film transistors connected to the firstpixel electrodes.

The thin film transistor array panel may further include a plurality ofthird signal lines intersecting the second signal lines, wherein a finalterminal of each of the second thin film transistors is connected to oneof the third signal lines and the second signal lines.

The final terminal of each of the second thin film transistors may beconnected to one of the third signal lines, and the thin film transistorarray panel may further include a plurality of third thin filmtransistors, each having three terminal connected to one of the secondsignal lines, one of the second pixel electrodes, and one of the firstsignal lines connected to a pixel area in an adjacent row.

At least one of the first pixel electrodes and the second pixelelectrodes includes at least one domain partitioning member. The thinfilm transistor array panel may further include a gate insulating layerdisposed between the first signal lines and the second signal lines, anda passivation layer disposed between the second signal lines and thefirst and the second pixel electrodes, wherein the coupling electrodesare preferably connected to the first pixel electrodes through contactholes at the passivation layer.

The thin film transistor array panel according to embodiments of thepresent invention is used for a panel for a liquid crystal display.

Advantageous Effect

A viewing angle of an LCD is enlarged by improving lateral visibility.

BEST MODE OF EMBODIMENTS

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinventions invention are shown. The present invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein.

In the drawings, the thickness of layers and regions are exaggerated forclarity. Like numerals refer to like elements throughout. It will beunderstood that when an element such as a layer, region or substrate isreferred to as being “on” another element, it can be directly on theother element or intervening elements may also be present. In contrast,when an element is referred to as being “directly on” another element,there are no intervening elements present.

Then, liquid crystal displays and thin film transistor panels thereforaccording to embodiments of this invention will be described in detailwith reference to the accompanying drawings.

FIG. 1 is a layout view of a TFT array panel for an LCD according to afirst embodiment of the present invention, FIG. 2 is a sectional view ofthe TFT array panel shown in FIG. 1 taken along the line II-II′, andFIG. 3 is an equivalent circuit diagram of an LCD according to the firstembodiment of the present invention.

An LCD according to an embodiment of the present invention includes alower panel (i.e., a TFT array panel), an upper panel (i.e., an oppositepanel) facing the lower panel, and a liquid crystal layer interposedbetween the two panels and including liquid crystal molecules aligned ina twisted nematic mode such that they are twisted from the lower panelto the upper panel.

First, the lower panel is described.

A plurality of first and second pixel electrodes 190 a and 190 bpreferably made of transparent conductive material such as ITO (indiumtin oxide) and IZO (indium zinc oxide) are formed on an insulatingsubstrate 110 preferably made of transparent insulating material such asglass. Each of the first pixel electrodes 190 a is connected to a firstthin film transistor TFT1 and receives image signal voltages therefrom,and each of the second pixel electrodes 190 b is connected to a secondthin film transistor TFT2 that is electrically connected to a previousgate line 121 for transmitting gate signals or scanning signals to aprevious pixel row and to a storage electrode line 131. The second pixelelectrode 190 b overlaps a coupling electrode 176 connected to the firstpixel electrode 190 a to be electromagnetically (capacitively) coupledtherewith. The first thin film transistor TFT1 is connected to a gateline 121 transmitting scanning signals and a data line 171 transmittingimage voltages and switches on or off the image signals to be suppliedto the first pixel electrode 190 a in response to the scanning signals.Here, the first and the second pixel electrodes 190 a and 190 b for areflective LCD may not include transparent material.

In the meantime, although it is not shown in the figures, the upperpanel is described now.

A black matrix for blocking light leakage between pixels, a plurality ofred, green, and blue color filters, and a common electrode preferablymade of transparent conductive material such as ITO and IZO forgenerating an electric field along with the pixel electrodes 190 a and190 b are formed a surface of an insulating substrate preferably made oftransparent insulating material such as glass, which faces the TFT arraypanel. The black matrix and the color filters may be provided on the TFTarray panel.

Now, a TFT array panel for an LCD according to the first embodiment isdescribed more in detail.

A plurality of gate lines 121 and a plurality of storage electrode lines131 extending in a transverse direction are formed on a lower insulatingsubstrate 110.

A plurality of portions of each gate line 121 expand upward and downwardto a plurality of gate electrodes 123 a of first thin film transistorsTFT1, and each gate lines 121 includes an end portion 125 having a largearea for connection with an external circuit.

In the meantime, a gate line 121 transmitting gate signals or scanningsignals to a previous pixel row has a plurality of portions forming gateelectrodes 123 b of second thin film transistors TFT2.

Each pixel electrode 131 includes a plurality of sets of storageelectrodes 133 a and 133 b branched therefrom. Two storage electrodes133 a and 133 b in a set of storage electrodes 133 a and 133 b arebranched out in a longitudinal direction and extend to edges of a pixelarea.

The gate lines 121 and the storage electrode lines 131 is preferablymade of metal such as Al, Al alloy, Ag, Ag alloy, Cr, Ti, Ta and Mo. Asshown in FIG. 2, the gate lines 121 and the storage electrode lines 131according to this embodiment including a single layer. However, they mayhave a dual-layered structure including a metal layer preferably made ofCr, Mo, Ti and Ta having excellent physical and chemical characteristicsand another metal layer preferably containing Al or Ag having lowresistivity. The gate lines 121 ad the storage electrode lines 131 maybe made of various metal or conductors other than those described above.

The gate lines 121 and the storage electrode lines 131 have inclinedside surfaces and the inclination angle relative to a horizontal surfaceis preferably 30-80°.

A gate insulating layer 140 preferably made of silicon nitride SiNx isformed on the gate lines 121 and the storage electrode lines 131.

On the gate insulating layer 140, a plurality of the data lines 171

a plurality of drain electrodes 175 of the first thin film transistorsTFT1, a plurality of coupling electrodes 176, and a plurality ofunder-bridge metal pieces 172 are formed. Each data line 171 extendssubstantially in the longitudinal direction, and it includes a pluralityof branches extending to the drain electrodes 175 to form sourceelectrodes 173 a of the first thin film transistors TFT1. Theunder-bridge metal pieces 172 are disposed on previous gate lines 121and include a plurality portions forming drain electrodes 175 b of thesecond thin film transistors TFT2. A plurality of source electrodes 173b of the second thin film transistors TFT2 are formed on the previousgate lines 121 and they are disposed opposite to the drain electrodes175 b of the second thin film transistors TFT2 with respect to theprevious gate lines 121. The coupling electrodes 176 are connected tothe drain electrodes 175 a of the first thin film transistors TFT1 anddisposed near the pixel areas to overlap the storage electrode lines131.

The data lines 171, the drain electrodes 175 a and 175 b, the couplingelectrodes 176, the source electrodes 173 a and 173 b, and theunder-bridge metal pieces 172 are preferably made of Cr or Al like thegate lines 121, and they may include a single layer or multiple layers.

A plurality of semiconductor stripes 151 are formed under the data lines171 and the drain electrodes 175 a and they extend substantially in thelongitudinal direction along the data lines 171. Each semiconductorstripe 151 preferably made of amorphous silicon has a plurality ofbranches extending toward the gate lines 123 a, the source electrodes173 a, and the drain electrodes 175 a and forming channel portions 154of the first thin film transistors TFT1. In addition, a plurality ofsemiconductor islands 155 forming channel portions of the second thinfilm transistors TFT2 are formed on the previous gate lines 121.

A plurality of ohmic contacts 161 are disposed between thesemiconductors 151 and the data lines 171 and the drain electrodes 175 afor reducing the contact resistance therebetween. The ohmic contacts 161are preferably made of silicide or amorphous silicon heavily doped withn type impurity. The ohmic contacts 161 include a plurality of ohmiccontacts 163 a and 165 a for the first thin film transistors TFT1disposed under the source electrodes 173 a and the drain electrodes 175a, and a plurality of ohmic contacts 163 b and 165 b for the second thinfilm transistors TFT2 are formed tinder the source electrodes 173 b andthe drain electrodes 175 b of the second thin film transistors TFT2.

A passivation layer 180 made of an inorganic insulator such as siliconnitride or an organic insulator such as resin is formed on the datalines 171, the drain electrodes 175 a and 175 b, the coupling electrodes176, and the under-bridge metal pieces 172.

The passivation layer 180 has a plurality of contact holes 181 a, 181 band 183 exposing at least a portion of the drain electrodes 175 a and175 b and the end portions 179 of the data lines 171, respectively. Inaddition, a plurality of contact holes 182, 184 and 185 exposing the endportions 125 of the gate lines 121 and portions of the storage electrodelines 131, respectively, penetrate the gate insulating layer 140 and thepassivation layer 180. In addition, the passivation layer 180 has aplurality of contact holes 186 exposing the source electrodes of thesecond thin film transistors TFT2.

A plurality of pixel electrodes the pixel electrodes 190 a and 190 b, aplurality of contact assistants 95 and 97, and a plurality of storagebridges 91 are formed on the passivation layer 180. The pixel electrodes190 a and 190 b, the contact assistants 95 and 97, and the storagebridges 91 is preferably made of a transparent conductor such as ITO(indium tin oxide) and IZO (indium zinc oxide) or an opaque conductorsuch as Al having excellent light reflectance.

The pixel electrodes 190 a and 190 b includes first pixel electrodes 190a and second pixel electrodes 190 b. The first pixel electrodes 190 aare connected to the drain electrodes 175 a of the first thin filmtransistors TFT1 through the contact holes 181 a, and the second pixelelectrodes 190 b are connected to the drain electrodes 175 b of thesecond thin film transistors TFT2 through the contact holes 181 b andoverlap the coupling electrodes 176. Accordingly, the second pixelelectrodes 190 b are electromagnetically (capacitively) coupled to thefirst pixel electrodes 190 a.

The storage bridges 91 connect two storage electrode lines 131 disposedopposite each other with respect to the gate lines 121. The storagebridges 91 contact the storage electrodes 133 a and the storageelectrode lines 131 through the contact holes 184 and 185 penetratingthe passivation layer 180 and the gate insulating layer 140. The storagebridges 91 are connected to the under-bridge metal pieces 172 throughthe contact holes 186. Accordingly, when the second thin filmtransistors operate responsive to gate-on signals applied to theprevious gate lines 121, the second pixel electrodes 190 b are suppliedwith a common voltage or a reference voltage applied to the storageelectrode lines 131. The storage bridges 91 electrically connect all thestorage electrode lines 131 on the lower substrate 110. The storageelectrode lines 131 are used for repairing the defects in the gate lines121 or the data lines 171, if necessary, and the under-bridge metalpieces 172 enhance the electrical connection between the gate lines 121and the storage bridges 91 when a laser beam is illuminated forrepairing.

The contact assistants 95 and 97 are connected to the end portions 125of the gate lines 121 and the end portions 179 of the data lines 171through the contact holes 182 and 183, respectively.

In the above-described LCD, the first pixel electrodes 190 a receive theimage signal voltages through the first thin film transistors TFT1,while the second pixel electrodes 190 b have changing voltages dependenton the capacitive coupling with the storage electrode lines 131.Therefore, absolute values of the voltages of the second pixelelectrodes 190 b are always higher than those of the first pixelelectrodes 190 a. In this way, two pixel electrodes disposed in a pixelarea but having different voltages compensate their voltages to reducethe distortion of a gamma curve.

Then, a reason why the voltage of a second pixel electrode 190 b ismaintained higher than that of a first pixel electrode 190 a isdescribed with reference to FIG. 3.

In FIG. 3, C_(LCA) indicates a liquid crystal capacitance between afirst pixel electrode 190 a and a common electrode of an opposite panel,and C_(STA) indicates a storage capacitance between the first pixelelectrode 190 a and a storage electrode line 131. C_(LCB) indicates aliquid crystal capacitance between a second pixel electrode 190 b andthe common electrode of the opposite panel, C_(STB) indicates a storagecapacitance between the second pixel electrode 190 b and the storageelectrode line 131, and C_(CPB) indicates a coupling capacitance betweena coupling electrode 176 and the second pixel electrode 190 b.

The voltage of the first pixel electrode 190 a with respect to a commonvoltage or a reference voltage applied to the common electrode of theopposite panel is denoted by Va(Vd1), and the voltage of the secondpixel electrode 190 b is denoted by Vb. The voltage distribution lawresults in:Vb≈1/(C ₁+2C ₂)×[(2−C ₃ /C ₂)×(C ₁ +C ₂)×Vd1].

The voltage Vb can be controlled such that the voltage Vb approaches thevoltage Va but always higher than the voltage Va by adjusting thecapacitances. Here, C₁=C_(LCA)+C_(STA), C₂=C_(CPB), andC₃=C_(LCB)+C_(STB). A parasitic capacitance between a gate electrode anda source electrode is neglected since it is trivial.

The arrangements of the first or the second thin film transistor TFT1 orTFT2 or the connection between the first and the second pixel electrodes190 a and 190 b can be variously modified, which will be described insecond to seventh embodiments.

Hereinafter, only the features distinguished from the first embodimentwill be described and remaining features that is the same as those ofthe first embodiment will be omitted.

FIG. 4 is a layout view of a TFT array panel for an LCD according to thesecond embodiment of the present invention, FIG. 5 is a sectional viewof the TFT array panel shown in FIG. 4 taken along the line V-V′, andFIG. 6 is an equivalent circuit diagram of an LCD according to thesecond embodiment of the present invention.

In the TFT array panel for an LCD according to the second embodiment, asecond thin film transistor TFT2 is driven though a previous gate line121 like the first embodiment, but it owns a gate electrode 123 commonlywith a first thin film transistor TFT1 and the first and the second thinfilm transistors TFT1 and TFT2 are disposed opposite with respect to agate line 121. A source electrode 173 b of the second thin filmtransistor TFT2 and a source electrode 173 a of the first thin filmtransistor TFT1 extend from a data line 171, a drain electrode 175 b ofthe second thin film transistor TFT2 extends opposite a drain electrode175 a of the first thin film transistor TFT1 with respect to the gateelectrode 123.

In the TFT array panel for an LCD according to the second embodiment ofthe present invention, although a second pixel electrode 190 b isinitially supplied with a pixel voltage supplied with a first pixelelectrode 190 a of a previous pixel row, it is supplied with a voltageVb dose to a voltage Va(Vd1) of the first pixel electrode 190 a when thepixels in a corresponding pixel row are driven since it is capacitivelycoupled with the first pixel electrode 190 a. The voltage Vb is givenfrom the voltage distribution law by:Vb≈1/(C ₁+2C ₂)×[(2−C ₃ /C ₂)×(C ₁ +C ₂)×Vd1+(C ₁ +C ₃)Vd2].

The voltage Vb can be controlled such that the voltage Vb approaches thevoltage Va but always higher than the voltage Va by adjusting thecapacitances and the TFT array panel according to the second embodimentof the present invention is preferably subject to column inversiontherefor. Here, the voltage Vd2 is the voltage initially supplied to thesecond pixel electrode 190 b when the second thin film transistor TFT2turns on.

The first and the second embodiments according to the present inventionthe second relates to the control of an effective driving voltagesupplied to the pixel electrode 190 b. However, the TFT array panel maybe modified such that the first pixel electrode 190 a is supplied with avoltage lower than a driving voltage transmitted by a data line, whilethe second pixel electrode 190 b is supplied with a voltage higher thanthe driving voltage, which will be described in detail with reference tothe figures.

FIG. 7 is a layout view of an LCD according to the third embodiment ofthe present invention and FIG. 8 is an equivalent circuit diagram of anLCD according to the third embodiment of the present invention.

Most of the configuration is the same as those shown in FIGS. 1 and 3.

However, a first pixel electrode 190 a is not connected to a first thinfilm transistor TFT1 through a contact hole in a passivation layer(indicated by 180 in FIG. 2), and it overlaps a coupling electrode 176such that it is electromagnetically (capacitively) coupled with thefirst thin film transistors TFT1.

In the TFT array panel for an LCD according to the third embodiment ofthe present invention, an effective pixel voltage supplied to a firstpixel electrode 190 a is smaller than a voltage Vd1 supplied through adata line 171. It is because that the first pixel electrode 190 a iscapacitively coupled with the coupling electrodes 176 connected to adrain electrode 175 a, the effective pixel voltage Va of the first pixelelectrode 190 a with respect to the common voltage is given from thevoltage distribution law by:Va=Vd1×[C _(CPA)/(C _(CPA) +C _(LCB))].

Since C_(CPA)/(C_(CPA)+C_(LCB)) is always lower than one, the voltage Vais always smaller than the voltage Vd1. Here, C_(CPA) indicates acoupling capacitance between the coupling electrodes 176 and the firstpixel electrode. 190 a.

The effective driving voltage Vb supplied to the second pixel electrode190 b is determined in the same way as the first embodiment.

FIG. 9 is a layout view of an LCD according to the fourth embodiment ofthe present invention and FIG. 10 is an equivalent circuit diagram of anLCD according to the fourth embodiment of the present invention.

Most of the configuration is the same as those shown in FIGS. 4 and 6.

However, the connection relation between first and second thin filmtransistors TFT1 and TFT2 and the first and the second pixel electrodes190 a and 190 b is substantially the same as that shown in FIGS. 7 and8.

In this case, an effective driving voltage Vb supplied to the firstpixel electrode 190 a is smaller than a voltage Vd1 transmitted by adata line 171 and an effective driving voltage Vb supplied to the secondpixel electrode 190 b is determined in the same way as the secondembodiment.

The LCD has a major disadvantage of its narrow viewing angle, andseveral suggestions increasing the viewing angle for overcoming thedisadvantage have been developed. Among these techniques, a methodprovides a plurality of cutouts or a plurality of protrusions on pixelelectrodes and a common electrode opposite each other and aligns liquidcrystal molecules vertical to upper and lower panels. The cutouts or theprotrusions can be applied to TFT array panels according to embodimentsof the present invention.

The cutouts provided both at the pixel electrodes and the commonelectrode give wide viewing angle by generating fringe field to adjustthe tilt directions of the liquid crystal molecules.

The provision of the protrusions both on the pixel electrode and thecommon electrode in the lower and upper panels distorts the electricfield to adjust the tilt directions of the liquid crystal molecules.

The fringe field for adjusting the tilt directions of the liquid crystalmolecules to form a plurality of domains is also obtained by providingthe cutouts at the pixel electrodes on the lower panel and theprotrusions on the common electrode on the upper panel.

The fifth embodiment of the present invention relates to a configurationhaving cutouts is described in detail.

FIG. 11 is a layout view of a TFT array panel for an LCD according tothe fifth embodiment of the present invention, FIG. 12 is a layout viewof a color filter panel for an LCD according to the fifth embodiment ofthe present invention, FIG. 13 is a layout view of an LCD the fifthembodiment of the present invention, and FIG. 14 is a sectional view ofthe LCD shown in FIG. 13 taken along the line XIV-XIV′.

An LCD according to the fifth embodiment of the present inventionincludes a lower panel, an upper panel facing the lower panel, and aliquid crystal layer interposed between the two panels and includingliquid crystal molecules aligned vertical to surfaces of the panels.

First, the lower panel is described.

A plurality of first and second pixel electrodes 190 a and 190 bpreferably made of transparent conductive material such as ITO (indiumtin oxide) and IZO (indium zinc oxide) are formed on an insulatingsubstrate 110 preferably made of transparent insulating material such asglass. The first and the second pixel electrodes 190 a and 190 b areconnected to first and second thin film transistors TFT1 and TFT2,respectively, like the first embodiment. Each of the second pixelelectrodes 190 b overlaps a coupling electrode 176 connected to a firstpixel electrode 190 a to be electromagnetically (capacitively) coupledtherewith. The second pixel electrode 190 b has a cutout 192. A lowerpolarizing plate 12 is attached to an outer surface of the insulatingsubstrate 110. Here, the first and the second pixel electrodes 190 a and190 b for a reflective LCD may not include transparent material, and inthis case, the lower polarizing plate 12 is unnecessary.

The upper panel is described now.

A black matrix 220 for blocking light leakage between pixels, aplurality of red, green, and blue color filters 230, and a commonelectrode 270 preferably made of transparent conductive material such asITO and IZO are formed on an inner surface of an insulating substrate210 preferably made of transparent insulating material such as glass.The common electrode 270 has a plurality of cutouts 271, 272 and 273.The black matrix 220 is disposed around pixel areas and it may overlapthe cutouts 271, 272 and 273 of the common electrode 270 for blockinglight leakage near edges of the cutouts 271, 272 and 273.

Now, a TFT array panel for an LCD according to the first embodiment isdescribed more in detail.

A pair of a first pixel electrode 190 a and a second pixel electrode 190b is divided by a gap that includes a pair of portions 191 and 193making 45 degrees with gate line 121 and a portion perpendicular to thegate lines 121. Each of the 45-degree portions 191 and 193 is longerthan the perpendicular portion. In addition, the 45-degree portions areperpendicular to each other.

A second pixel electrode 190 b has a cutout 192 that extends from aright edge of the second pixel electrode 190 b toward a left edgethereof and has an expanded inlet.

The first pixel electrode 190 a and the second pixel electrode 190 bhave inversion symmetry with respect to a line that bisects a pixel areadefined by intersections of the gate lines 121 and data lines 171 (andextends parallel to the gate lines 121).

A black matrix 220 for blocking light leakage is formed on an upperinsulating substrate 210 and a plurality of red, green, and blue colorfilters 230 are formed on the black matrix 220. A common electrode 270,which is preferably made of transparent conductive material such as ITOand IZO and includes a plurality of sets of cutouts 271-273 are formedon the color filters 230.

A set of the cutouts 271, 272 and 273 in the common electrode 270interpose the 45-degree portions of the gap between the pixel electrodes190 a and 190 b and they include oblique portions parallel to the45-dgree portions and end portions overlapping edges of the pixelelectrodes 190 a and 190 b. The end portions of the cutouts 271-273include longitudinal end portions and transverse end portions.

The above-described TFT array panel and color filler panel are alignedand assembled and a liquid crystal material is injected therebetween andvertically aligned, thereby preparing a basic structure of the LCDaccording to an embodiment of the present.

When the TFT array panel and the color filter panel are aligned witheach other, a set of the cutouts 271, 272 and 273 in the commonelectrode 270 partition each of the pixel electrodes 190 a and 190 binto a plurality of subareas, according to this embodiment, foursubareas as shown in FIG. 13. As shown in FIG. 13, each subarea iselongated to have a width direction and a length direction.

Portions of a liquid crystal layer 3 disposed between the subareas ofthe pixel electrodes 190 a and 190 b and the subareas of the commonelectrode 270 corresponding thereto are referred to as subregions, andthe subregions are classified into four kinds depending on averagelong-axis directions of liquid crystal molecules contained therein underthe application of an electric field, which are referred to as domains.

In the meantime, although the first to the fifth embodiments connect asecond pixel electrode 190 b to a second thin film transistor TFT2, thesecond pixel electrode 190 b may be connected to two thin filmtransistors.

FIG. 15 is an equivalent circuit diagram of an LCD according to thesixth embodiment of the present invention.

Referring to FIG. 15, an LCD according to the sixth embodiment of thepresent invention adds the second thin film transistor (TFT2 shown inFIG. 6) of the second embodiment into the connection configuration ofthe first embodiment as a third thin film transistor TFT3.

FIG. 16 is an equivalent circuit diagram of an LCD according to theseventh embodiment of the present invention.

Referring to FIG. 16, an LCD according to the sixth embodiment of thepresent invention adds the second thin film transistor (TFT2 shown inFIG. 10) of the fourth embodiment into the connection configuration ofthe third embodiment as a third thin film transistor TFT3.

The above-described configuration improves lateral visibility of an LCD,thereby widening a viewing angle.

While the present invention has been described in detail with referenceto the preferred embodiments, those skilled in the art will appreciatethat various modifications and substitutions can be made thereto withoutdeparting from the spirit and scope of the present invention as setforth in the appended claims. In particular, the cutouts formed in thepixel electrodes and the common electrode have various modifications.

The invention claimed is:
 1. A liquid crystal display comprising: afirst insulating substrate; a gate line formed on the first insulatingsubstrate and including first and second gate electrodes; a storageelectrode line formed on the first insulating substrate; a gateinsulating layer covering the gate line and the storage electrode line;first and second amorphous silicon layers formed on the gate insulatinglayer; a data line formed on the gate insulating layer and including afirst source electrode disposed on the first amorphous silicon layer atleast in part; a second source electrode disposed on the secondamorphous silicon layer at least in part; first and second drainelectrodes formed on the first and the second amorphous silicon layersat least in part and disposed opposite the first and the second sourceelectrodes, respectively; a coupling electrode formed on the gateinsulating layer and extended from the first drain electrode; apassivation layer formed on the data line, the first and the seconddrain electrodes, and the coupling electrode; a first pixel electrodethat is formed on the passivation layer and is connected to or overlapsthe first drain electrode and the coupling electrode; a second pixelelectrode insulated from the first pixel electrode, connected to thesecond drain electrode, and overlapping the coupling electrode at leastin part; a second insulating substrate facing the first insulatingsubstrate; and a common electrode formed on the second insulatingsubstrate, wherein the coupling electrode is connected to the firstdrain electrode.
 2. The liquid crystal display of claim 1, wherein thesecond source electrode is connected to the storage electrode line orthe data line.
 3. The liquid crystal display of claim 2, wherein thesecond source electrode is connected to the storage electrode line, andthe liquid crystal display further comprises a third gate electrodeconnected to the gate line, a third source electrode connected to thedata line, and the third drain electrode connected to the second pixelelectrode.
 4. The liquid crystal display of claim 2 or 3, wherein thefirst drain electrode is connected to the coupling electrode.
 5. Theliquid crystal display of claim 2, wherein the coupling electrode isconnected to the first pixel electrode through a contact hole at thepassivation layer.
 6. The liquid crystal display of claim 2, furthercomprising: a first domain partitioning member disposed on at least oneof the first and the second substrates; and a first domain partitioningmember disposed on at least one of the first and the second substratesand partitioning a pixel area into a plurality of domains along with thefirst domain partitioning member.
 7. A liquid crystal display,comprising: a first substrate; plurality of pixels disposed in a matrixon the first substrate, each pixel comprising a first pixel electrodeand a second pixel electrode, wherein the first pixel electrode and thesecond pixel electrode are separated from each other and are disposed inone pixel area, the first pixel electrode is electrically connected to afirst transistor, and the second pixel electrode is electricallyconnected to a second transistor; a second substrate facing the firstsubstrate and having a common electrode; a coupling electrode whichapplies an electric field to one of the first pixel electrode and thesecond pixel electrode; and a liquid crystal layer interposed betweenthe first substrate and the second substrate and comprising a pluralityof liquid crystal molecules disposed in a first liquid crystal regioncorresponding to the first pixel electrode and a second liquid crystalregion corresponding to the second pixel electrode, the first liquidcrystal region being different from the second liquid crystal region,the first liquid crystal region and the second liquid crystal regioncorresponding to the one pixel area, wherein the liquid crystal layer ofthe first liquid crystal region is divided into at least 4 domains andthe liquid crystal layer of the second liquid crystal region is dividedinto at least 4 domains, wherein the domain is defined by an orientationdirection of liquid crystal molecules when a voltage is applied to thefirst pixel electrode and the second pixel electrode, wherein anelectric field generated between the first pixel electrode and thecommon electrode of the one pixel area is different from an electricfield generated between the second pixel electrode and the commonelectrode of the one pixel area, wherein the coupling electrode isconnected to one of the first pixel electrode and the second pixelelectrode, and the coupling electrode overlaps the other of the firstpixel electrode and the second pixel electrode.
 8. The liquid crystaldisplay of claim 7, wherein the pixel comprises at least one of thefirst pixel electrode, the second pixel electrode and the commonelectrode further comprise at least one domain partitioning memberforming the domain of the liquid crystal layer.
 9. The liquid crystaldisplay of claim 8, wherein the at least one domain partitioning memberhas at least one slit.
 10. The liquid crystal display of claim 7,wherein the coupling electrode contacts one of the first pixel electrodeand the second pixel electrode via a contact hole through an insulatinglayer.
 11. The liquid crystal display of claim 7, further comprises astorage capacitance line capacitatively coupled with one of the firstpixel electrode and the second pixel electrode.
 12. The liquid crystaldisplay of claim 11, wherein the storage capacitance line is overlappedwith a portion of one of the first pixel electrode and the second pixelelectrode.
 13. The liquid crystal display of claim 12, wherein thecoupling electrode is overlapped with the storage capacitance line. 14.The liquid crystal display of claim 7, wherein a surface area of thefirst pixel electrode is different from a surface area of the secondpixel electrode.
 15. The liquid crystal display of claim 14, wherein ashape of a boundary of the first pixel electrode is different from ashape of a boundary of the second pixel electrode.
 16. The liquidcrystal display of claim 15, wherein the boundary of the first pixelelectrode and the boundary of the second pixel electrode are bothpolygonal.
 17. The liquid crystal display of claim 14, wherein thesurface area of the first pixel electrode is 30% to 70% of a surfacearea of an individual pixel.
 18. The liquid crystal display of claim 7,wherein a shape of a boundary of the first pixel electrode is differentfrom a shape of a boundary of the second pixel electrode.
 19. The liquidcrystal display of claim 18, wherein the boundary of the first pixelelectrode and the boundary of the second pixel electrode are bothpolygonal.
 20. The liquid crystal display of claim 7, wherein the firstpixel electrode and the second pixel electrode are disposed in a samelayer on the first substrate.